Dear Hermann the Cherusker,
Although I'd agree that the "boundaries" between these orientations are not hard and fast, nonetheless, I assure you that there are men who overwhelmingly are attracted sexually to men, and men who are overwhelmingly attracted sexually to women.
Men who are overwhelmingly attracted sexually to women predominate in society, probably on the order of 97% or more. Men who are overwhelmingly attracted sexually to men perhaps constitute 1% - 3% of the population.
These sexual attractions are relatively stable (although not necessarily unchangeable) and persist as an attribute of the psyche of the individual. I'm agnostic as to from where deviant same-sex attractions arise (although they are stable, I see no evidence that they are in-born, or genetic).
There are certainly ambiguities at the boundaries of these populations. Some number of men who are predominantly heterosexual are also willing to engage in homosexual activities, and some number of men who are predominantly homosexual will engage in sex with women. But the overwhelming majority of heterosexual men find the thought of sexual contact with another man to be repulsive.
Men who are overwhelmingly attracted sexually to women may also find thoughts of sodomy with women pleasant and attractive, even though these same men have absolutely no attraction to men, and the overwhelming number of these men are repulsed by the thought of sexual contact with other men. In fact, I know plenty of men who are repulsed by male-male sexual contact, but find the thought of sodomy with attractive women to be a pleasant thought.
As for what men do in extreme situations, that's another story. Nonetheless, I'll note that my own anecdotal evidence (taken from men who have served time in prison) indicates that it is a small number of aggressors who prey on a somewhat larger number of coerced victims, but even so, that most men do not have sexual contact with other men while in prison.
It is a serious problem, in that with 2 million men in prison in the United States, several hundred thousand men are involved, and most of them as victims. Nonetheless, even the pressure and distortion of prison life does not cause a large percentage of men to take sexual gratification from homosexual acts.
sitetest
All the same, there is no creature as the homosexual, as if this is some inborn trait, rather than a mental tendency a person can free himself from with grace, just as others must free themselves from nymphomania, kleptomania, or congenital lying.
Homosexuality appears stable because it is quasi-illegal to try to convert people from it.